The invention relates generally to the production of steel and, more particularly, to a method and arrangement for the continuous production of steel.
A method for melting scrap, particularly steel scrap, is described in the German Pat. No. 1,800,610. Here, scrap is admitted into a vertically arranged melting chamber so as to form a column of scrap. The scrap is melted by directing a flame against the scrap column from beneath the latter. The cross-section of the column of scrap remains substantially constant and, in order to melt the scrap, a flame of plate-shaped configuration is used which is centered with respect to the cross-section of the scrap column. The flame extends across the major portion of the cross-section of the column of scrap. The plate-shaped flame is located so far above the bottom of the melting chamber that the liquid melt which flows off is able to accumulate to some extent over the bottom of the melting chamber and thus serve as a heat-insulator for the heat-resistant lining of the latter. The flame is produced with the aid of a lance burner which is located on the axis of the melting chamber and which either extends through the scrap column or extends into the melting chamber through the bottom thereof.
In this method, the melt which flows off may be fed directly into a container which accommodates liquid pig iron in order to be then further processed. The further processing of this starting metal, namely, melt and pig iron, is conventionally performed by transporting the container with the starting metal to a Siemens-Martin furnace, an electric furnace, a converter or the like and then introducing the starting metal into the furnace or converter.
The above-outlined method has the disadvantage that the liquid starting metal is superheated to only a relatively slight extent. Thus, it is possible to hold this starting metal in the container for only short periods of time without the formation of incrustations and, consequently, the liquid starting metal may be transported over only relatively short distances. Moreover, this method is suitable only for the production of steel on a batch-type or discontinuous basis.
In the publication "Stahl und Eisen," volume 92, pages 515-518, (1972), it has been proposed to combine the continuous scrap-melting operation according to the German Pat. No. 1,800,610 with a continuous process for the production of pig iron such as, for instance, in a cupola furnace. In this manner, it was intended to arrive at a continuous steel production process wherein purification, refining, superheating, alloying and deoxidation must follow in a continuous operation. However, here there exists always the precondition that pig iron which comes, for example, from a blast furnace or a cupola furnace, must be used. This leads to the disadvantage that the process is inherently tied in to the use of furnaces of this type.
Further steel production processes are also known from the publication "Stahl und Eisen," volume 60, pages 1146-1153 (1970) according to each of which a reaction chamber is provided for the boiling out of impurities from, or for the purification or refining of, the continuously flowing pig iron-like material. Here, it is further necessary to blow with, or blow in, oxygen for the purifying or refining operation. A precondition for all of these processes is likewise the provision of pig iron. Scrap is added in these processes but the only purpose of the scrap additions is as a cooling agent for the continuously purified pig iron. However, another disadvantage of these steel production processes, which are reliant upon the provision of continuously flowing pig iron, resides precisely in the fact that the continuous or regulatable introduction of cooling scrap is one of the unsolved problems associated therewith.